Created
February 11, 2015 21:01
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Drag and drop, resize and xhr post
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| <!doctype html> | |
| <html lang="en"> | |
| <head> | |
| <meta charset="UTF-8"> | |
| <link rel="stylesheet" href="styles.css"> | |
| <title>Filereader</title> | |
| </head> | |
| <body> | |
| <div id="dragarea" class="drag-area"></div> | |
| <script src="scripts.js"></script> | |
| </body> | |
| </html> |
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| if (!HTMLCanvasElement.prototype.toBlob) { | |
| Object.defineProperty(HTMLCanvasElement.prototype, 'toBlob', { | |
| value: function (callback, type, quality) { | |
| var binStr = atob(this.toDataURL(type, quality).split(',')[1]), | |
| len = binStr.length, | |
| arr = new Uint8Array(len); | |
| for (var i=0; i<len; i++) { | |
| arr[i] = binStr.charCodeAt(i); | |
| } | |
| callback(new Blob([arr], { type: type || 'image/png' })); | |
| } | |
| }); | |
| } | |
| (function(window, document) { | |
| 'use strict'; | |
| var target = document.getElementById('dragarea'); | |
| var fileToDataUrl = function(file) { | |
| var reader = new window.FileReader(); | |
| return new Promise(function(resolve, reject) { | |
| reader.onload = function(event) { | |
| resolve(event.target.result); | |
| }; | |
| reader.readAsDataURL(file); | |
| }); | |
| }; | |
| var getImageData = function(dataUrl, width, height) { | |
| var canvas = document.createElement('canvas'); | |
| var context = canvas.getContext('2d'); | |
| var image = new Image(); | |
| return new Promise(function(resolve, reject) { | |
| image.onload = function() { | |
| var img = this; | |
| width == null && (width = Math.round(img.width * height / img.height)); | |
| height == null && (height = Math.round(img.height * width / img.width)); | |
| canvas.width = width; | |
| canvas.height = height; | |
| context.drawImage(img, 0, 0, img.width, img.height, 0, 0, width, height); | |
| canvas.toBlob(function(blob) { | |
| resolve(blob) | |
| }, 'image/png'); | |
| }; | |
| image.src = dataUrl; | |
| }); | |
| }; | |
| var filesUpload = function(files) { | |
| var xhr = new XMLHttpRequest(); | |
| var file; | |
| if (files.length) { | |
| file = files[0]; | |
| if (file.type.match(/image.*/) && 0 < file.size) { | |
| fileToDataUrl(file) | |
| .then(function(dataUrl) { | |
| getImageData(dataUrl, 200) | |
| .then(function(blob) { | |
| console.log(blob) | |
| xhr.open('POST', '/upload'); | |
| xhr.setRequestHeader('Content-Type', blob.type); | |
| xhr.send(blob); | |
| }); | |
| }); | |
| } | |
| } | |
| }; | |
| target.addEventListener('dragenter', function(event) { | |
| }); | |
| target.addEventListener('dragleave', function(event) { | |
| }); | |
| target.addEventListener('dragover', function(event) { | |
| event.dataTransfer.dropEffect = 'copy'; | |
| event.stopPropagation(); | |
| event.preventDefault(); | |
| }); | |
| target.addEventListener('drop', function(event) { | |
| event.stopPropagation(); | |
| event.preventDefault(); | |
| filesUpload(event.dataTransfer.files) | |
| }); | |
| })(window, window.document) |
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| .drag-area { | |
| width: 500px; | |
| height: 400px; | |
| background-color: darkgray; | |
| } |
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